bsd builds broken

[dhuseby]

some type mismatches, missing constants, etc.

[dhuseby]

@alexcrichton this is the libc side of the fix. rust-lang/rust#31230 is the libstd side. together the bsd builds are green again.

[dhuseby]

@alexcrichton as soon as this lands, i'll update the liblibc version in https://github.com/rust-lang/rust